Polymer dispersed liquid crystal (PDLC) is a material prepared by mixing low molecular weight liquid crystal molecules and prepolymer under polymerization in certain conditions to form micron-sized liquid crystal droplets evenly dispersed in the polymer network, by using the dielectric anisotropy of liquid crystal molecules it has an electro-optic response property, and works mainly in a scattering state and a transparent state, by controlling the voltage to adjust its gray scale. The working principle of PDLC is that PDLC films cannot form a regular electric field without applying external voltage. The optical axis orientation of liquid crystal particles is random and disordered, the reflectivity does not match the reflectivity of the polymer, the incident light is seriously scattered, and the PDLC thin film is opaque or translucent. After an external voltage is applied, the optical axis of the liquid crystal particles is aligned perpendicular to the thin film surface, that is, consistent with the direction of the electric field. The reflectivity of the PDLC thin film substantially matches the reflectivity of the polymer, there is no obvious interface, a substantially uniform medium is formed so the incident light does not scatter, and the PDLC film is transparent. Therefore, when an external electric field is applied, the PDLC thin film has an optical switching characteristic, and its degree of transparency also increases along with a certain curve as the applied voltage increases.
Due to its good electro-optical properties, high sensitivity, wide dynamic range, high resolution and fast response, PDLC can save polarizer film, save cost and power consumption compared to existing VA or IPS LCDs. However, at this stage, the PDLC adopting traditional pixel design has disadvantages such as low contrast ratio. The contrast ratio can be improved by increasing the thickness of the liquid crystal layer. However, an increase of the thickness of the liquid crystal layer leads to a drastic increase of the driving voltage, thereby increasing the driving cost and power consumption, and even affecting the liquid crystal lifetime.